In particular in the field of the transport of vehicles on the deck of a railway car or an auto carrier, it is known to use tie-down systems to immobilize the wheels of the vehicles on said deck. Of course, very similar tie-down systems can also be provided to immobilize any type of load on a deck.
These tie-down systems generally comprise a strap connected to tie-down hooks. A tie-down hook is generally provided at one end of the strap, while the other end is engaged with a tensioning device, for example a strap tensioner with ratchet or a dedicated device provided on the deck of the transport vehicle. The strap is typically passed over a wheel of a vehicle to be immobilized, then tensioned so as to press the wheel downward on the deck. A tie-down hook is generally provided in front of and behind the wheel to be immobilized so as to connect the strap locally to the deck. More specifically, the strap is typically connected to an end hook; it slides in another tie-down hook situated between the wheel and the strap tensioner. Seen from above, the tie-down hooks are aligned optimally in the axis of the wheel. However, since the tensioner can be located below the body of the car, it is generally offset toward the outside. This results in lateral forces primarily at the sliding hook that tend to tilt it outward.
With the aim of allowing a strap to be fastened on the deck, the deck of railway cars or auto carriers has oblong through orifices extending longitudinally in the axis of the transport vehicle. The curved end of the tie-down hooks is then inserted into these through orifices in order to catch at their front or rear border. When the strap is tensioned, the free end of the hooks presses against the deck, bearing on the underside thereof.
With the increased weights of cars, the tension present in the tie-down systems must be increased. As a result, the traditional hooks tend to damage the deck of the transport vehicles. It has in fact been observed that the free end of the tie-down hooks had a tendency to deform the material on the underside of the plates, sometimes leading to the breaking of the decking of the decks, and thus to poor restraint of the vehicle.
This problem should therefore be resolved, preferably without having to modify the deck of the transport vehicles.
Known from documents EP 3238990 A1, U.S. Pat. Nos. 4,960,353 A and 7,871,228 B2 is a tie-down hook including a cylindrical and rectilinear spatula. Due to its rectilinear shape having a curve in a single plane, the spatula does not allow a slight pivoting of the lateral extensions relative to the deck when they are pressed against the underside thereof. Thus, the spatula may damage the underside of the deck when the strap is urged laterally.
Known from document AU 611700 B2 is a tie-down hook that is not intended to be inserted into through orifices provided in the deck, but into loops attached on said deck. At its free end, this hook includes a round part with angular edges that could damage the underside of the deck when it is pressed against the underside of the deck.